import { createLogger } from '@sim/logger'
import { type NextRequest, NextResponse } from 'next/server'
import { gmailLabelSelectorContract } from '@/lib/api/contracts/selectors/google'
import { parseRequest } from '@/lib/api/server'
import { authorizeCredentialUse } from '@/lib/auth/credential-access'
import { validateAlphanumericId } from '@/lib/core/security/input-validation'
import { generateRequestId } from '@/lib/core/utils/request'
import { withRouteHandler } from '@/lib/core/utils/with-route-handler'
import { getScopesForService } from '@/lib/oauth/utils'
import { refreshAccessTokenIfNeeded, ServiceAccountTokenError } from '@/app/api/auth/oauth/utils'

export const dynamic = 'force-dynamic'

const logger = createLogger('GmailLabelAPI')

export const GET = withRouteHandler(async (request: NextRequest) => {
  const requestId = generateRequestId()

  try {
    const parsed = await parseRequest(gmailLabelSelectorContract, request, {})
    if (!parsed.success) return parsed.response
    const { credentialId, labelId } = parsed.data.query
    const impersonateEmail = parsed.data.query.impersonateEmail || undefined

    const labelIdValidation = validateAlphanumericId(labelId, 'labelId', 255)
    if (!labelIdValidation.isValid) {
      logger.warn(`[${requestId}] Invalid label ID: ${labelIdValidation.error}`)
      return NextResponse.json({ error: labelIdValidation.error }, { status: 400 })
    }

    const credAccess = await authorizeCredentialUse(request, {
      credentialId,
      requireWorkflowIdForInternal: false,
    })
    if (!credAccess.ok || !credAccess.credentialOwnerUserId) {
      logger.warn(`[${requestId}] Credential access denied`, { error: credAccess.error })
      return NextResponse.json({ error: credAccess.error || 'Unauthorized' }, { status: 401 })
    }

    const accessToken = await refreshAccessTokenIfNeeded(
      credentialId,
      credAccess.credentialOwnerUserId,
      requestId,
      getScopesForService('gmail'),
      impersonateEmail
    )

    if (!accessToken) {
      return NextResponse.json({ error: 'Failed to obtain valid access token' }, { status: 401 })
    }

    logger.info(`[${requestId}] Fetching label ${labelId} from Gmail API`)
    const response = await fetch(
      `https://gmail.googleapis.com/gmail/v1/users/me/labels/${labelId}`,
      {
        headers: {
          Authorization: `Bearer ${accessToken}`,
        },
      }
    )

    logger.info(`[${requestId}] Gmail API response status: ${response.status}`)

    if (!response.ok) {
      const errorText = await response.text()
      logger.error(`[${requestId}] Gmail API error response: ${errorText}`)

      try {
        const error = JSON.parse(errorText)
        return NextResponse.json({ error }, { status: response.status })
      } catch (_e) {
        return NextResponse.json({ error: errorText }, { status: response.status })
      }
    }

    const label = await response.json()

    let formattedName = label.name

    if (label.type === 'system') {
      formattedName = label.name.charAt(0).toUpperCase() + label.name.slice(1).toLowerCase()
    }

    const formattedLabel = {
      id: label.id,
      name: formattedName,
      type: label.type,
      messagesTotal: label.messagesTotal || 0,
      messagesUnread: label.messagesUnread || 0,
    }

    return NextResponse.json({ label: formattedLabel }, { status: 200 })
  } catch (error) {
    if (error instanceof ServiceAccountTokenError) {
      return NextResponse.json({ error: error.message }, { status: 400 })
    }
    logger.error(`[${requestId}] Error fetching Gmail label:`, error)
    return NextResponse.json({ error: 'Failed to fetch Gmail label' }, { status: 500 })
  }
})